Good point about the closeness to the audience and the risk of being up there all alone Virginia. I can't sing a song unaccompanied unless it touches me in some way outside of the normal range of emotion.
I have a number of songs that I sing unacompanied but I am aware that, most of the time, the audience can only take just so much, so I try to limit them to gain the maximum impact.
Of course, a lot depends on the audience and the venue. I have been in sessions where no one who sang used an instrument and others where the use of instruments was mixed. In each case no one seemed to mind if there were or were not instruments being played.

troll